Does a criminal defendant have a constitutional right to cross-examine experts who prepare reports that other prosecution experts rely upon as evidence in a criminal trial? That question has been presented to the Wisconsin Supreme Court for resolution.

Rozerick Mattox was charged with reckless homicide for supplying heroin to a drug user who allegedly died from a heroin overdose. During Mattox’s trial, a medical examiner who conducted an autopsy gave expert testimony about the alleged victim’s cause of death. Basing her opinion in part on a toxicology report prepared by an out-of-state laboratory analyst, the medical examiner concluded that the alleged victim died from a heroin overdose.

Experts typically rely upon reports or analyses that are prepared by other experts. The lab analyst who prepared the toxicology report did not testify at Mattox’s trial. The issue with which Wisconsin’s appellate courts are struggling with is whether Mattox was deprived of his constitutional right to confront an expert witness when that witness prepared a report but did not testify (and thus could not be cross-examined) during the trial.

Medical Examiner’s Testimony

Dr. Zelda Okia performed the autopsy on the deceased drug user. She testified that certain physical findings, including a pulmonary embolism, cerebral edema (swelling of the brain), and the elevated weight of the lungs, were consistent with a drug overdose. Those symptoms could have been produced by an overdose of drugs other than heroin. She also saw more than a dozen needle marks on the deceased’s arm.

Dr. Okia also testified that she collected various fluid samples and sent them to St. Louis University for a toxicology analysis. Dr. Okia told the jury that the county medical examiner’s office had used St. Louis University for many years because its laboratory was accredited and was run by a board certified toxicologist. She testified that she was satisfied with toxicology reports that the laboratory had prepared in the past.

The toxicology report indicated that a fatal level of morphine was present in the fluids. Heroin, among other opiates, metabolizes into morphine. The toxicology report also identified the presence of a metabolite that is specific to heroin. Dr. Okia concluded from the report that heroin, rather than some other opiate, caused the drug user’s death.

Hearsay and Expert Reports

Mattox was charged with murder on the theory that he supplied heroin to the deceased drug user. If the death was caused by the drug user’s ingestion of some other opiate that the drug user obtained from a different source, Mattox would have been entitled to an acquittal. The issue of whether heroin, as opposed to another opiate, caused the drug user’s death was therefore critical to Mattox’s conviction.

Mattox’s attorney objected that the toxicology report was hearsay. Applying a common hearsay exception, the trial judge ruled that the report was admissible because it contained “facts or data” that was “of a type reasonably relied upon by experts in the particular field in forming opinions or inferences upon the subject” of the expert’s testimony. The judge also ruled that the toxicology report was not offered to prove that Mattox delivered heroin to the deceased but was received only for the limited purpose of explaining how the medical examiner formed her opinion.

The trial court’s reasoning is problematic. It is true that the toxicology report was not offered to prove that Mattox supplied heroin to the deceased drug user. It seems evident, however, that the report was offered to prove that the drug user died of a heroin overdose. In the absence of the toxicology report, Dr. Okia had no basis for determining whether heroin, as opposed to some other opiate, caused the drug user’s death. Since proving that heroin caused the drug user’s death was critical to the charge that Mattox committed reckless homicide, the toxicology report was not used for a “limited purpose” but as substantive evidence of Mattox’s guilt.

Whether or not the toxicology report was admissible as an exception to Wisconsin’s hearsay rule, the larger question is whether the author of the report should have been required to testify so that the opinions expressed in the report could have been subjected to cross-examination. The answer to that question is governed by United States Supreme Court cases that address the Confrontation Clause.

Confrontation of Expert Witnesses

The United States Constitution guarantees criminal defendants the right to face-to-face confrontation of witnesses who make testimonial statements. A statement is testimonial if it is given with the expectation or understanding that it might be used as evidence in court.

The toxicologist at St. Louis University who prepared the laboratory analysis was certainly aware that it might be used as evidence in a criminal trial. Two Supreme Court cases establish that a lab report is testimonial and is therefore inadmissible as evidence to establish an element of a crime unless the analyst who prepared the report testifies and is subject to cross-examination.

The medical examiner in Mattox’s case relied upon evidence other than the lab report to conclude that Mattox died from a drug overdose. Mattox’s conviction, however, depended on evidence that Mattox died from using the heroin that Mattox supplied, rather than some other opiate that someone else may have supplied. The critical evidence in support of that element of the offense was supplied by the lab report, not by the medical examiner’s independent observations. The lab report therefore seems to fit the definition of testimonial evidence.

The Wisconsin Court of Appeals noted a conflict in its own precedent regarding the admissibility of lab reports when the expert who prepared the report did not testify. The court’s prior cases seemed to draw a distinction between an expert who relied entirely upon a lab report to establish cause of death and an expert who considered a lab report as one piece of evidence to support a conclusion as to cause of death. Whether that distinction is consistent with United States Supreme Court precedent is unclear.

Bringing Lab Analysts to Court

The Wisconsin Court of Appeals wants to punt Mattox’s case to the Wisconsin Supreme Court, which is better situated to resolve the conflict in Wisconsin precedent. If the court agrees to review the case, it will need to decide whether laboratory analysts must provide expert testimony in person in cases like Mattox’s. If so, the cost of criminal trials will increase, since prosecutors may need to bring out-of-state analysts to court to testify as experts.

That increased cost may be a small price to pay to preserve the constitutional right to cross-examine testimonial witnesses. Since there have been cases across the country in which lab analysts have turned out to be unqualified to render objective expert opinions, it cannot be said that cross-examining a lab analyst is necessarily a meaningless exercise. Whether the Wisconsin Supreme Court will accept the case and, if so, how it will rule, may not be known for several months.

About T.C. Kelly

Prior to his retirement, T.C. Kelly handled litigation and appeals in state and federal courts across the Midwest. He focused his practice on criminal defense, personal injury, and employment law. He now writes about legal issues for a variety of publications.

About T.C. Kelly

Prior to his retirement, T.C. Kelly handled litigation and appeals in state and federal courts across the Midwest. He focused his practice on criminal defense, personal injury, and employment law. He now writes about legal issues for a variety of publications.